Technology Tales

Adventures in consumer and enterprise technology

Getting custom Python imports to work in Visual Studio Code

18th February 2022

While I continue to use Spyder as my preferred Python code editor, I also tried out Visual Studio Code. Handily, this Integrated Development Environment also has facilities for working with R and Julia code as well as MarkDown text editing and adding the required extensions is enough for these applications; it helps that there is an unofficial Grammarly extension for content creation.

My Python code development makes use of the Pylance extension and it works a little differently from Spyder when it comes to including files using import statements. Spyder will look into the folder where the base script is located but the default behaviour of Pylance is that it looks in the root path of your workspace. This meant that any code that ran successfully in Spyder failed in Visual Studio Code.

The way around this was to add the required location using the python.analysis.extraPaths setting for the workspace. That meant opening Settings by navigating to File > Preferences > Settings in the menu system and entering python.analysis.extraPaths into the search box. That took me to the section that I needed and I then clicked on Add Item before entering the required path and clicking on the OK button. That was enough to fix the problem and all worked as it should after that.

Using multi-line commenting in Perl to inactivate blocks of code during testing

26th December 2019

Recently, I needed to inactivate blocks of code in a Perl script while doing some testing. This is something that I often do in other computing languages so I sought the same in Perl. To do that, I need to use the POD methodology. This meant enclosing the code as follows.

=start

<< Code to be inactivated by inclusion in a comment >>

=cut

The =start line could use any word after the equality sign but it seems that =cut is needed to close the multi-line comment. If this was actual programming documentation, then the comment block should include some meaningful text for use with perldoc but that was not a concern here since the commenting statements would be removed afterwards anyway and it is good practice not to leave commented code in a production script or program to avoid any later confusion.

In my case, this facility allowed me to isolate the code that I needed to alter and test before putting everything back as needed. It also saved time since I did not need to individually comment out every executable line because multiple lines could be inactivated at a time.

Selecting SAS code in the Program Editor on UNIX

5th June 2007

Here’s a possible bugbear with programming using the SAS Display Manager in UNIX, selecting sections of code and running them. In the installations that I have encountered, the mouse selection is not retained so the code selection cannot be run. There is a fix for this and it is not the most obvious. Going to the Preferences dialogue box (Tools > Options > Preferences… from the menu bar) and selecting the Editing tab brings up the screen below:

SAS Editing Preferences on UNIX

Ensuring that "Automatically store selection" is switched off, as shown above, will allow one to select and submit sections of code from a SAS program like what is normal practice with Windows SAS. It isn’t an obvious solution but it does the trick for me.

Another way to look through WordPress code

10th August 2008

At times in the past, I have complained about there not being sufficient documentation of the actual code used in WordPress itself. True, there is the venerable Codex but that can be incomplete and any extra help is always useful. Peter Westwood (a.k.a westi) has generated documentation from the code itself and put it up on the web for all to peruse. While we are on the subject of information on the more advanced aspects of WordPress, blogs by Mark Jaquith and Andrew Ozz are also worth a look. As the cliché goes, every little helps…

HennessyBlog theme update

12th February 2007

Over the weekend, I have been updating the theme on my other blog, HennessyBlog. It has been a task that projected me onto a learning curve with the WordPress 2.1 codebase. I have collected what I encountered so I know that it’s out there on the web for you (and I) to use and peruse. It took some digging to get to know some of what you find below. Any function used to power WordPress takes some finding so I need to find one place on the web where the code for WordPress is fully documented. The sites presenting tutorials on how to use WordPress are more often than not geared towards the non-techie rather than code cutters like myself. Then again, they might be waiting for someone to do it for them…

The changes made are as follows:

Tweaks to the interface

These are subtle with the addition of navigation controls to the sidebar and the change in location of the post metadata being the most obvious enhancements. “Decoration” with solid and dashed lines (using CSS border attributes rather than the deprecated hr tagset) and standards compliance links.

Standards compliance

Adding standards compliance links does mean that you’d better check that all is in order; it was then that I discovered that there was work to be done. There is an issue with the WordPress wpautop function (it lives in the formatting.php file) in that it sometimes doesn’t add closing tags. Finding out that it was this function that is implicated took a trip to the WordPress.org website; a good rummage in the wp-includes folder does a lot but it can’t achieve everything.

Like a lot of things in the WordPress code, the wpautop function isn’t half buried. The the_content function (see template-functions-post.php) used to output blog entries calls get_content function (also in template-functions-post.php) to extract the data from mySQL. The add_filter function (in plugin.php) associates the wpautop function and others with get_the_content function and the p tags get added to the output.

To return to the non-ideal behaviour that caused me to start out on the above quest, an example is where you have an img tag enclosed by div tags. The required substitution involves the use of regular expressions that work most of the time but get confused here. So adding a hack to the wpautop function was needed to change the code so that the p end tag got inserted. I’ll be keeping an eye out for any more scenarios like this that slip through the net and for any side effects. Otherwise, compliance is just making sure that all those img tags have their alt attributes completed.

Tweaks to navigation code

Most of my time has been spent on tweaking of the PHP code supporting the navigation. Different functions were being called in different places and I wanted to harmonise things. To do this, I created new functions in the functions.php for my theme and needed to resolve a number of issues along the way. Not least among these were regular expressions used for subsetting with the preg_match match that weren’t to my eyes Perl-compliant, as would be implied by the choice of function. I have since found that PCRE’s in PHP use a more pragmatic syntax but there remained issues with the expressions that were being used. They seemed to behave OK in their native environment but fell out of favour within the environs of my theme. Being acquainted with Perl, I went for a more familiar expression style and the issue has been resolved.

Along the way, I broke the RSS feed. This was on my off-line test blog so no one, apart from myself, that is, would have noticed. After a bit of searching, I realised that some stray white-space from the end of a PHP file (wp-config.php being a favourite culprit), after the PHP end tag in the script file as it happens, was finding its way into the feed and causing things to fall over. Feed readers don’t take too kindly to the idea of the XML declaration not making an appearance on the first line of the file. The refusal of Firefox to refresh things as it should caused some confusion until I realised that a forced refresh of the feed display was needed -- sometimes, it takes a while for an addled brain to think of these kinds of things.

Some SAS Macro code for detecting the presence or absence of a variable in a dataset

4th December 2013

Recently, I needed to put in place some code to detect the presence or absence of a variable in a dataset and I chose SAS Macro programming as the way to do what I wanted. The logic was based on a SAS sample that achieved the same result in a data step and some code that I had for detecting the presence or absence of a dataset. Mixing the two together gave me something like the following:

%macro testvar(ds=,var=);

%let dsid=%sysfunc(open(&ds,in));
%let varexist=%sysfunc(varnum(&dsid,&var));
%if &dsid > 0 %then %let rc=%sysfunc(close(&dsid));

%if &varexist gt 0 %then %put Info: Variable &var is in the &ds dataset;
%else %put Info: Variable &var is not in the &ds dataset;

%mend testvar;

%testvar(ds=dataset,var=var);

What this does is open up a dataset and look for the variable number in the dataset. In datasets, variables are numbered from left to right with 1 for the first one, 2 for the second and so on. If the variable is not in the dataset, the result is 0 so you know that it is not there. All of this is what the VARNUM SCL function within the SYSFUNC macro function does. In the example, this resolves to %sysfunc(varnum(&dsid,var)) with no quotes around the variable name like you would do in data step programming. Once you have the variable number or 0, then you can put in place some conditional logic that makes use of the information like what you see in the above simple example. Of course, that would be expanded to something more useful in real life but I hope it helps to show you the possibilities here.

Getting Pylance to recognise locally installed packages in VSCode running on Linux Mint

17th December 2024

When using VSCode on Linux Mint, I noticed that it was not finding any Python package installed into my user area, as is my usual way of working. Thus, it was being highlighted as being missing when it was already there.

The solution was to navigate to File > Preferences > Settings and click on the Open Settings (JSON) icon in the top right-hand corner of the app to add something like the following snippet in there.

"python.analysis.extraPaths": [
"/home/[user]/.local/bin"
]

Once you have added your user account to the above, saving the file is the next step. Then, VSCode needs a restart to pick up the new location. After that, the false positives get eliminated.

System error codes for Windows

9th May 2008

Windows system error codes can be indecipherable so it’s useful to have a list. Microsoft has one on its Microsoft Learn website that may help. However, the decodes may not as explicit as I would like but they’re better than nothing when you don’t get anything other than the number.

A web development toolbox

23rd March 2007

Having been on a web-building journey from Geocities to having a website with my own domain hosted by Fasthosts, it should come as no surprise that I have encountered a number of tools and technologies over this time and that my choices and knowledge have evolved too. I’ll muse over the technologies first before going on to the tools that I use.

Technologies

XHTML

When I started building websites, HTML 4 was not long in existence and I devoured most if not all of Elizabeth Castro’s Peachpit Visual Quickstart guide to the language within a weekend. Having previously used fairly primitive WYSIWYG tools like Netscape Composer and Claris Home Page, it was an empowering experience and the first edition (it is now on its third) of Jennifer Niederst Robbins’ Web Design in a Nutshell took things much further, becoming something of a bible for a number of years.

When it first appeared, XHTML 1.0 wasn’t a major change from HTML 4, but its stricter more XML-compliant syntax was meant to point the way to the future and semantic markup was at its heart at least as much as it was for HTML 4. XHTML 2.0 is on the horizon and after the modular approach of XHTML 1.1 (which I have never used), it will be interesting to see how it develops. Nevertheless, there is a surprising development in that some people are musing over the idea of having an HTML 5. Let’s hope that the (X)HTML apple cart doesn’t get completely overturned after some years of relative stability. I still bear scars from the browser wars raging in the 1990’s and don’t want to see standards wars supplanting the relative peace that we have now. That said, I don’t mind peaceful progression.

CSS

Only seems to be coming into its own in the last few years and is truly a remarkable technology despite the hobbles that MSIE places on our ambitions. CSS Zen Garden has been a major source of ideas; I wouldn’t have been able to customise this blog as much as I have without them. I was an early adopter of the technology and got burnt by inconsistent browser support; Netscape 4 was the proverbial bête noir back then, fulfilling the role that MSIE plays today. In those days, it was the idea of controlling text display and element backgrounds from a single place that appealed. Since then, I have progressed to using CSS to replace table-based layouts and to control element positioning. It can do more…

JavaScript

Having had a JavaScript-powered photo gallery before my current Perl-driven one, I can say that I have definitely sampled this ever-pervasive scripting language. Being a client-side language rather than a server-side one, it does place you rather at the mercy of the browser purveyors, and it never ceases to amaze me that there is a buzz around AJAX because of this. In fact, the abundance of AJAX cross-browser function libraries is testimony to the need for browser-specific code. Despite my preferences for server-side scripting, I still find a use for JavaScript, and its main use for me these days is to dynamically control CSS elements to do such things as control the height of a page element or whether it is shown or not. Apparently, CSS may get some dynamic capabilities in the future and reduce my dependence on JavaScript. Meanwhile, Jeremy Keith’s DOM Scripting (Friends of Ed) will prove as much of an asset as it has done.

XML

These days, a lot of the raw data underlying my personal website is stored in XML. I did try to dynamically transform the display of the XML into something meaningful with CSS and XSLT when I first scaled its dizzy heights, but I soon resorted to other techniques. Browser support and the complexity of what I required were the major contributors to this. The new strategy involved two different approaches. The first was to create PHP/XHTML pages from the precursor XML offline, and this is how I generate the website’s directory pages. The other one is to process the XML as text to dynamically supply an XHTML page as the user visits it; this is the way that the photo gallery works.

Perl

This still powers all of my photo gallery. While thoughts of changing it all to PHP linger, there is a certain something about the Perl language that keeps it there. I suppose it is that PHP is entangled in the HTML while Perl encases the whole business, and I am reasonably familiar with its syntax these days, which is why it still does a lot of the data processing grunt work that I need.

PHP

PHP is everywhere these days, though it doesn’t attract quite the level of hype that used to be the case. It still appears with its sidekick MySQL in many website applications. Blogging software such as WordPress and content management systems like Drupal, Mambo and Joomla! wouldn’t exist without the pair. It appears on my website as the glue that holds my visitor directories together and is the processing engine of my WordPress blog. And if I ever get to a Drupal element to the site, by no means a foregone conclusion though I am spending a lot of time with it at the moment, PHP will continue its presence in my website scripting as it powers that too.

Applications

Macromedia HomeSite

I have a liking for hand coding, so this does most of what I need. When Macromedia (itself since taken over by Adobe, of course) took over Allaire, HomeSite sadly lost its WYSIWYG capability, but the application still soldiers on even though Dreamweaver offers a lot to code cutters these days. Nevertheless, it does have certain advantages over Dreamweaver: it is a fleeter beast to start up and colour codes Perl syntax.

Macromedia Dreamweaver

There was a time when Dreamweaver was solely a tool for visual web page development, but the advent of Dreamweaver UltraDev added server-side development capabilities to the Dreamweaver family. These days, there is only one Dreamweaver version, but UltraDev’s capabilities still live on in the latest version and I would not be surprised if they were taken further in these database-driven times.

Nowadays, Dreamweaver isn’t an application where I spend a great deal of time. In former times, when my site was made up of static HTML pages, I used Dreamweaver a lot, even if its rendering capabilities were a step behind the then-current browser versions. I suppose that it didn’t fit the way in which I worked, but its template-driven workflow would have been a boon back then.

However, my move from a static site to a dynamic one, starting with my photo gallery, has meant that I haven’t used it as much since then. However, with my use of PHP/MySQL components on my site. Its server-side abilities could get the level of investigation that its PHP/MySQL capabilities allow.

Altova XMLSpy Professional

Adding MySQL databases to my web hosting costs money, not a lot, but it could be spent on other (more important?) things. Hence, I use XML as the data store for my photo gallery and XML files are pre-processed into XHTML/PHP pages for my visitor directories before uploading onto the server.

I use XMLSpy to edit and manage the XML files that I use: its ability to view XML in grid format is a killer feature as far as I am concerned and XML validation also proves very useful; particularly when it comes to ensuring that DTD’s and XML files are in step and for the correct coding of XSLT files. There are other features that I need to explore and that would also take my knowledge of the XML further to boot, not at all a bad thing.

Saxon

For processing XML into another file format such as XHTML, you need a parser and I use the free version of Saxon to do the needful, Saxonica offers commercial versions of it. There is, I believe, a parser in XMLSpy, but I don’t use it because Saxon’s command line interface fits better into my workflow. This is a Perl-driven process where XML files are read and XSLT files, one per XML file, are built before both are fed to Saxon for transforming into XHTML/PHP files. It all works smoothly and updating the XML inputs is all that is required.

AceFTP

If I were looking for an FTP client now, it would be FileZilla, but AceFTP has served me well over the last few years, and it looks as if that will continue. It does have some extra features over FileZilla: transfers between remote sites, and scheduling, for example. I have yet to use either, but they look valuable.

Hutmil

In bygone days when I had loads of static HTML files, making changes was a bit of a chore if they affected every single file. An example is changing the year on the copyright message on the page footers. Hutmil, which I found on a magazine cover-mounted disc, was a great time saver in those days. Today, I achieve this by putting this information into a single file and getting Perl or PHP to import that when building the page. The same “define once, use anywhere” approach underlies CSS as well, and scripting very usefully allows you to take that into the XHTML domain.

Apache

Apache is ubiquitous these days, and both the online and offline versions of my site are powered by it. It does require some configuration, but it is a very powerful piece of kit. The introduction of 2.2.x meant a big change in the way that configuration files were modularised and while most things were contained in a single file for 2.0.x, the settings are broken up into different files in 2.2.x, and it can take a while to find things again. Without having it on my home PC, I would not be able to use Perl, PHP or MySQL. Apart from this, I especially like its virtual site capability; very useful for offline development.

WordPress

My hosting supplier offers blogs on Blogware, but that didn’t offer the level of configuration that I would have liked. It is true that this is probably true of any host of blogs. I can’t speak for Blogger, but WordPress.com does have its restrictions too. To make my hillwalking blog fit in with the appearance of my photo gallery, I went popped over to WordPress.org to download WordPress so that I could host a blog myself and have maximum control over its appearance. WordPress supports themes, so I created my own and got my blog pages looking as if they are part of my website, rather than looking like something that was bolted on. Now that I think of it, what about WordPress supporting user-created themes? I support that there is the worry of insecure PHP code but what about it?

MySQL

I am between minds on whether this is a technology or a tool. SQL certainly would be a technology standard, but I am not so clear on what MySQL would be. In any case, I have classed it as a tool and a very useful one at that. It is the linchpin for my WordPress blogs and, if I go for a content management system like Drupal, its role would surely grow. While I do have a lot of experience with using SAS SQL and this helps me to deal with other varieties, there is still a learning curve with MySQL that gets me heading for a good book and Kofler’s The Definitive Guide to MySQL5 (Apress) seems to perform more than adequately in this endeavour.

Paint Shop Pro

As someone who hosts an online photo gallery, it won’t come as a surprise that I have had exposure to image editors. Despite various other flirtations, Paint Shop Pro has been my tool of choice over the years, but it is now set to be usurped by a member of Adobe’s Photoshop family. Paint Shop Pro does have books devoted to it, but it appears that Photoshop gets better coverage and I feel that my image processing needs to be taken up a gear, hence the potential move to Photoshop

What about a book on WordPress development?

7th October 2007

Here’s something that I would really appreciate: a book on code cutting for WordPress customisation and extension. Having the Codex is all very fine but having a dead tree compendium that you can peruse at your leisure is a definite bonus. If there was a way to get the Codex on PDF and print it all off for easier reading, that would be progress. I believe that a publisher did plan to bring to the market something like what I want but author and publisher parted company, a pity. It would be great to see something like Apress’ Pro Drupal Development for WordPress. What about it, Automattic folks?

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